Hello World! I'm talking about variables in Alice3.
I have an Alice World with a chicken and I want the chicken to jump up and down.
I don't really know exactly how much I want him to jump, but I want him to jump down by the same amount.
So what I'm going to do is pick variable,
and for the type I'm going to select double.
There's four types you can pick:  Double are numbers with decimal places,
Integer is whole numbers,
Boolean are things that can be true or false,
and Strings are words like "hello" and "goodbye".
So we pick double and give it a name amountToJump.
and initially I'm going to give it a value of .5,  say OK.
Then select the chicken and we're going to do MoveDirection.Up
by amountToJump.
and then MoveDirection.DOWN by amountToJump.
and if we run our movie he jumps up.  That be a little bit more than I want.
So I'm going to change this to a custom DecimalNumber and put in something like .35.
and I don't have to change that in two places I only have to change it in one place,
and when it says Move up amountToJump,   it will use that value .35
and when it says move down it will move that same amount,the amountToJump.
and I can experiment with this until I have the chicken jumping just the right amount
that I want him to jump.
Of course, it would be nice if his wings would flap and whatever,
but there's our variable.